Preparation of addendum copolymer



Patented Aug. 16, 1949 PREPARATION OF ADDENDUM COPOLYMER Howard L.Gerhart, Milwaukee, Wis., assignor to Pittsburgh Plate Glass Company,Allegheny County, Pa., a corporation of Pennsylvania No Drawing.Application June 21, 1946, Serial No. 678,363

9 Claims. (01. zoo-45.4)

The present invention relates to synthetic resins obtained by conjointaddendum polymerization of active oiefinic groups in a plurality ofunsaturated compounds and it has particular relation to the preparationof such resins by the conjoint polymerization of a polymerizablemonolefin and a, p-unsaturatecl, a, p-dicarboxylic acid and a glycolicester of a tetrahydrophthali c. acid or anhydride. The application is acontinuation-inpart of my copending application Serial No. 512,768,filed December 3, 1943, and entitled Preparation of addendum copolymer,now abandoned.

One object of the invention is to provide olefin polymer resins of theabove indicated type which are very hard, tough, and which arethermosetting.

A second object is to provide polymerizable mixtures which willpolymerize rapidly and at low temperatures to the desired state.

These and other objects will be apparent from the followingspecification and the appended claims.

Resins have heretofore been prepared by conjointly polymerizing oz,B-unsaturated, a, B-dicarboxylic acids such as maleic acid (or itsanhydride) with a polymerizable unsaturated hydrocarbon containing asingle active or ethylenic double bond such as styrene. These resins areheat softenable, low in impact strength, and are hard to plasticize.leach out when the resin is contacted with a solvent and in manyinstances they tend to escape by evaporation.

In my copending application Serial No. 407,003, filed August 15, 1941,and entitled Resinous composition and the method of preparing the same,Patent No. 2,361,019, is disclosed a resin obtained by conjointlypolymerizing a polymerizable monolefin such as styrene, an a,fi-unsaturated, a, s-dicarboxylic acid such as maleic acid and apolyester of a glycol such as diethylene glycol and one of the a,B-unsaturated, a, fi-dicarboxylic acids (or anhydrides) such as a secendportion of maleic acid.

This reaction proceeds very rapidly at moderate temperatures and theproduct is hard, tough, impact resistant, and resistant to softening byheat. Apparently the unsaturated valences of the nucleus of the a,B-unsaturated acid in the polyester retain sufficient reactivity thatthey will enter into conjoint polymerization with the otherconstituents. The resultant product is hard and tough and of goodresistance to impact. There is no tendency to loose plasticizer byevaporation or by the action of solvents. In other words, the resin bodyis homogeneous and not a mixture. The resin components, beforepolymerization has gone too far, can be cast in molds or introduced byimpregnation into cloth or ad- Plasticizers are also likely to 2 mixedwith fibers or fillers. The mixture can then be polymerized to a hard,tough state to provide castings, laminates, etc.

The present invention is based upon the discovery that the a,,B-dicarboxylic, a, B-unsaturated acid esters of dihydroxy alcohols,notably the alk-ane diols or the dihydroxy ethers derived bycondensation thereof, can be replaced in the foregoing esters bycorresponding esters of tetrahydrophthalic acid or its analogues toprovide products which, with styrene and maleic anhydride alsopolymerize quickly and at low temperatures to a hard, tough state.

The tetrahydrophthalic acid (or anhydride) and homologues contemplatedherein can be easily prepared by subjecting an a, fi-unsaturated cis a,fl-dicarboxylic acid such as maleic acid (in anhydride form) orchlorom-aleic acid or their homologues to a Diels-Alder type reactionwith a conjugate dienehydrocarbon such as butadiene, cyclopentadieneisoprene, or cyclohexadiene.

The formula of the anhydride of tetrahydrophthalic acid may be written:

o=o I E It is derived from maleic anhydride and butadiene.

The formula of endomethylene delta 4 tetrahydrophthalic acid anhydrideor 3,6 endomethylene 1,2,3,6 tetrahydrophthalic anhydride (known ascarbic acid anhydride) derived from cyclopentadiene and maleic acid iswritten:

Ha I CH-CiO II CH2 0 HC\ -C=0 The reaction is discussed in greaterdetail in copending application Ser, No. 470,028, filed December 24,1942, and entitled Preparation of tetrahydrophthalic anhydrides, HowardL. Gerhart and Leon Adams, inventors, now Patent No. 2,423,234, July 1,1947.

In the present application, both the anhydrides of tetrahydrophthalicacids and the free acids from which they are derived are contemplatedand interchangeably can undergo esteriflcation with dihydroxy alcoholsto form the esters contemplated.

The acids or anhydrides will react with dihydroxy alcohols such asglycol, diethylene glycol, triethylene glycol, trimethylene glycol, ortetra- -o-c-o-o-c-o-cH,0H,-0-c-o-0 oH,cHr-

ll H H II I H H I from endomethylene tetrahydrophthalic acid and glycol.

It is to be observed that the cyclic residues of the acid molecule inthe ester linkage each include an olefin linkage or double bond. Thepotential reactivity of this double bond is very high even though it isin a cyclic structure and is remote from the carboxyls, so that when thepolyester is heated during the last stages of the esterification whenthe acid number approaches 10, the molecular chains cross link throughthe double bonds to form a three dimensional polymer which is veryinsoluble. Likewise a soluble polymer having an acid number of 40 orless will absorb oxygen at the double bonds and be converted to apartially oxidized resin which may easily become insoluble. Thus, it isseen that the double bond will very easily engage in polymerizationreactions. Therefore, it is desirable to discontinue esterificationbefore the gel stage is reached. Also an inert atmosphere should bemaintained over the reactants and the resultant ester to preventpolymerization by oxidation.

Esters can be made with many common polyhydroxyl compounds but theesters which are most useful are those from alcohols having two hydroxylgroups, such as ethylene glycol, diethylene glycol, triethylene glycol,tetraethylene glycol, trimethylene glycol, etc. A very small amount ofglycerine may be used to replace a portion of the glycol in thepreparation of these esters. The

. rapidly as it is formed. Heating is continued at 220 C. until theliquid ester has an acid number of 40 or less. The ester is then cooledand stored in an inert atmosphere.

The reaction may also be conducted in a solvent substantially asfollows:

Example B Charge 146 parts tetrahydrophthallc anhyhydride, 116 partsdiethylene glycol, and 20 parts xylol into a container equipped with aside arm take-off. Heat the mixture to boil olf the xylol glycerinetends to make the polyesters less soluble. The most desirable esters arethose having an acid value of 40 or less, preferably below about 30 butnot so low as to be unduly gelled. The acid value may be as low as 5 or10. Usually the dihydroxy alcohol is employed in a ratio near molar withrespect to the dicarboxylic acid component, but may be somewhat lowerand may be considerably higher, e. g. 5 or 20% either way. These estersare prepared in the presence of an inert gas totally free of oxygen andthey may be prepared by a method which involves the use of a solvent tofacilitate the removal of the water. The procedure follows the generalmethods well known in the preparation of the polyester type resins. Thefollowing examples are illustrative of such methods:

Example A A mixture of 164 parts of endomethylene tetrahydrophthalicanhydride ,and 116 parts diethylene glycol is heated as rapidly as isconvenient to 180 C. under air reflux condensation. The

and water rapidly. Separate the water from the xylol and return thelatter to the container substantially as rapidly as it distills.Continue to reflux until the acid number of the mixture is below 40 butnot substantially below 10. Pass a rapid stream of inert gas through theliquid to free the finished ester of most of the xylol. Remove the lasttraces of the x lol at reduced pressures again in an inert atmosphere.

In the examples, the proportions are by weight.

It is again emphasized that these esters contain double bonds in themolecule and although they are not contiguous to the 0:,[3-di031b0XYlgroups, they still retain a high degree of reactivity and are capable ofentering into addendum reactions with styrene and mil-dicarboxylic,(1,5- unsaturated acids or anhydrides to form complex polymers that arevery hard, tough, and which are thermoset to an infusible state. Any ofthe glycols including 1,2 or 1,3 propylene glycol, ethylene, diethylene,trlethylene and tetraethylene glycol can be employed in this reaction,as in Examples A and B.

Resins as herein contemplated comprise as components:

(A) A polyester of a tetrahydrophthalic acid and a glycol;

(B) A monomeric olefin capable of cross linking the polyester moleculesby addition; and

(C) An c p-unsaturated, p-dicarboxylic acid or anhydride, e. g. maleicanhydride.

The following constitute generalizations upon the compositions and theconditions of reaction involved in their preparation:

The ratio of styrene to polyester in the formulation preferably is suchthat for each 100 parts by weight of these two components the polyesterwill constitute 20 to parts. The maleic anhydride should be employed ina ratio within a. range of A to 20 or 45.4 parts by weight per parts ofstyrene-polyester mixture.

Temperatures of cure preferably attain a range of at least or 200 F.mold temperature, and may be much higher, for example, up to 275 or 300F. or other temperatures so long as the product is not excessivelydiscolored, or the components volatilized to an excessive degree.

Time of cure is variable dependent upon more rapidly than massivearticles and require less curing time. Plates up to about inch inthickness will adequately cure in about 5 to 30 minutes and most massivearticles may require a total of several hours, e. g. up to 5 or 6 hours.

Prolongation oi. the final heating period after the cure is completed ispermissible but usually is uneconomical in commercial operations.

Catalysts usually are desirable in the polymerizable mixtures but may beomitted if speed of cure is not an object. Catalysts are ofthe typecommonly employed in addendum reactions involving polymerization byaddition of unsaturated bonds. Usually the catalysts include a peroxidesuch as benzoyl peroxide, diacetylperoxide, tertiary butylhydroperoxide, tertiary butyl peroxide, acetyl benzoyl peroxide andtertiary butyl perbenzoate. These may be employed in appropriate ratio,e. g. .05 to 5% weight of resiniilable mixture.

The following are typical of mixtures of the esters with styrene anda.,B-dicarboxylic, a,fi-unsaturated acids or anhydrides which can beprepared and polymerized in accordance with the provisions of theinvention.

Composition Reaction Conditions Tempera- Descri tion ture, Deof t egrees 0. Product Parts by weight Time in Compound Hours EXAMPLE I lMaleic Anhydride Styrene Diethylene Glycol ester of endomethylenetetrahydrophthalic anhydride.

Benzoyl Peroxide 100 Hard, translucent.

EXAMPLE II Diethylene glycol ester of endomethylene tetrahydrophthallc 2Extremely acld hard and y e tough Maleic anhydride. Benzoyl peroxide-..

EXAMPLE III Triethylene glycol ester of endomethylene tetrahydrophthalic 6 100 Hard, transacld. l u c e n t Styrene resin.

Maleic anhydride- Benzoyl peroxide.

EXAMPLE IV Tetraethylene glycol ester of endors rsy rep 1; a 1c acid 100Very hard Styrene surface.

Maleic anhydride- Benzoyl peroxide.

In Examples II, III and IV the maleic anhydride is in a proportion of28.3 parts per 100 parts of styrene and polyester mixture.

The compositions in the following examples were used to cast sheets ofplastic according to the following procedure: The components of themixtures were stirred (with warming 1! necessary) and the well-mixedliquids were poured into a cell consisting of two pieces of plate glassseparated by a synthetic rubber gasket inch thick. The cell was placedin an oven at 167 F. for sixty minutes, after which the oven temperaturewas raised to 250 F. for 60 minutes. This schedule is more than enoughto completely cure the examples listed below:

Example V Parts Ethylene glycol polyester of endomethylenetetrahydrophthalic acid Styrene 30 Maleic Anhydride Benzoyl peroxide 2.5

This composition cures to give a clear rigid The resin from this mixtureis rigid, hard and very slightly translucent.

Example VII Parts Propylene glycol polyester of endomethylenetetrahydrophthalic acid Styrene 20 Maleic anhydride 1 Diacetyl peroxide2.5

The fully cured resin is a very hard clear rigid structure.

Example VIII Parts Diethylene glycol polyester of an equimolar mixtureof endomethylene tetrahydrophthalic and phthalic acids Styrene 10 Maleicanhydride; 2

Benzoyl peroxide l; 2.5

The cured composition is a soft transparent adhesive resin.

Example. IX

7 Parts Ethylene glycol (1 mol), diethylene glycol (9 mols) polyester ofendomethylene tetrahydrophthalic acid 60 Styrene 40 Maleic anhydride 20Benzoyl peroxide 2.5

The cured resin is moderately flexible and slightly translucent.

In these examples, maleic anhydride can be replaced by chloromaleicanhydride, tetrachloromaleic anhydride, or methyl substituted maleicanhydride and the endomethylene tetrahydroemployed may be any of theformulations previously described.

(X) In laminating applications, fabric is soaked in the resin monomersand the impregnated pieces are placed in a pile between two platens. Theresins will be completely cured in 5 to 30 minutes at platentemperatures of 200 to 275 F. when the thickness of the finishedlaminate is A; inch or less.

(Y) In casting applications it is desirable to allow the monomers to setup or gel at relatively low temperatures and to follow this with afurther cure at relatively higher temperatures. The catalyzed resins aregelled in the mold at from 120 to 170 F. (mold temperature) for from to180 minutes followed by a cure at 200 to 275 F, (mold temperature) forfrom 30 to 120 minutes. In the case of casting applications, the use offrom .05 to 1% tertiary butyl hydroperoxide is recommended in place ofthe benzoyl peroxide as given in the examples.

The embodiments of the invention herein described are merely by way ofexample. It will be apparent to those skilled in the art that numerousmodifications may be made therein without departure from the spirit ofthe invention or the scope of the appended claims.

I claim:

1. A process of preparing a new resinous product which comprisesconjointly polymerizing by heating approximately 15 parts maleicanhydride, 13 parts styrene, 15 to 35 parts diethylene glycol ester ofendomethylene 1, 2, 3, 6 tetrahydrophthalic acid.

2. A process of preparing a new resinous product which comprisesconjointly polymerizing approximately 15 parts maleic anhydride, 18parts styrene, 15 to 35 parts diethylene glycol ester of endomethylene1, 2, 3, 6 tetrahydrophthalic acid by heating the mixture to atemperature of ap proximately 60 to 100 C.

3. A process of preparing a resinous product which comprises heating amixture of an a,fiunsaturated, il-dicarboxylic acid, a polyester of analkane diol and endomethylene delta 4 tetrahydrophthalic acid andstyrene to a temperature of 180 to 300 F. for a period of about fiveminutes to five hours dependent upon the thickness and hardness of theproduct; the ratios of the components being A to 20 parts by weight0:,[3-1111- saturated, a,fi-dicarboxylic acid, styrene and polyestertogether being 100 parts by weight, the proportion of the polyesterbeing A to 9 times by weight that of the styrene.

dihydroxy ether of an alkane diol and endomethylene delta 4tetrahydrophthalic acid and styrene to a temperature of 180 to 300 F.for a period of about five minutes to five hours dependent upon thethickness and hardness of the product; the ratios of the componentsbeing V to 20 parts by weight, a, 3--unsaturated, il-dicarboxylic acid,styrene and polyester together being parts by weight, the proportion ofthe polyester being A to 9 times by weight that of the styrene.

5. A process of preparing a resinous product which comprises heating amixture of maleic anhydride, a polyester of an alkane diol andendomethylene delta 4 tetrahydrophthalic acid and styrene to atemperature of to 300 F. for a period of about five minutes to fivehours dependent upon the thickness and hardness of the product; theratios of the components being A to 20 parts by weight, lap-unsaturated,a,B-dicarboxylic acid, styrene and polyester together being 100 parts byweight, the proportion of the polyester being A to 9 times by weightthat of the styrene.

6. As a new resinous product, the copolymer of styrene, a compound of aclass consisting of alpha beta ethylenically unsaturated, alpha betadicarboxylic acids and the anhydrides thereof and a polyester of analcohol of a class consisting of alkane diols and the dihydric ethersthereof and endomethylene A 4 tetrahydrophthalic anhydride, thecomponents of said resin being in the proportions of A to 45.4 parts ofalpha beta ethylenically unsaturated, alpha beta dicarboxylic acid andthe styrene and the polyester together constituting 100 parts, of whichthe polyester constitutes 20 to 90 parts.

7. A resinous product as defined in claim 6 in which 10 to 75% of theendomethylene A 4 tetrahydrophthalic acid of the polyester is replacedby a saturated dicarboxylic acid.

8. A resinous product as defined in claim 6, in which endomethylenedelta 4 tetrahydrophthalic acid is replaced by phthalic acid to theextent of one mol of the latter per mol of the former.

9. A resinous product as defined in claim 6 in which 10 to 75% of theendomethylene delta 4 tetrahydrophthalic acid of the polyester isreplaced by an acid of a class consisting of a saturated dicarboxylicacid and phthalic acid.

HOWARD L. GERHART.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,319,826 Pellett May 25, 19432,359,038 Hopff Sept. 26, 1944 2,361,019 Gerhart Oct. 24, 1944 2,369,689Robie Feb. 20, 1945 2,421,876 Gerhart June 10, 1947

